feat: per-ingredient category selection for shopping list transfer (closes #33)

When adding ingredients in the meal editor, each ingredient now has a
category dropdown. Categories are stored on the ingredient and applied
automatically when transferring to the shopping list, so items appear
pre-grouped by category without manual re-sorting.

public/locales/ar.json

@@ -226,6 +226,8 @@
     "addIngredient": "إضافة مكون",
     "ingredientNamePlaceholder": "المكون",
     "ingredientQtyPlaceholder": "الكمية",
+    "ingredientCategoryLabel": "الفئة",
+    "ingredientCategoryDefault": "متنوعات",
     "removeIngredient": "إزالة المكون",
     "transferLabel": "نقل المكونات إلى قائمة التسوق",
     "transferNow": "نقل الآن",
@@ -596,4 +598,4 @@
     "unitMonth": "شهر",
     "unitMonths": "أشهر"
   }
-}
+}